Characteristics of Measles Cases -- United States, 1981

CDC has received detailed written information concerning
investigations of 1,759 (58.0%) of the 3,032 measles cases
provisionally reported in the United States in 1981. This
information, submitted voluntarily by 35 states and 2 local health
departments, has been reviewed to determine age, immunity status,
and
school and day-care-center attendance of the patients. These data
have been useful in classifying measles cases by preventability,
and
measles patients by age and accessibility to school- and
day-care-center based control measures.*

Of 1,759 persons with measles, 1,061 (60.3%) were school age,
5-19
years old (Table 1); an additional 547 measles cases (31.1%)
involved
preschool children. The other 151 patients (8.6%) were not in
school-age or preschool groups.

Of the 1,759 measles cases, 780 (44.3%) were classified as not
preventable because the patients were either too young or too old
for
routine vaccination, or because they had adequate evidence of
immunity
to measles. Of the 979 potentially preventable cases, 661 (37.6%
of
the total 1,759) were readily accessible to control measures, since
the affected children attended schools or day-care centers. The
other
318 persons (18.1%) were not readily accessible--not of school age
or
not known to attend a day-care center.

Of the 1,061 measles cases involving school-age children (Table
2), 638 (60.1%) were identified as potentially preventable. The
remaining 423 children, although accessible, did not have
preventable
cases because they had adequate evidence of immunity to measles. A
considerably higher percentage of preventable cases occurred in
older
schoolchildren.

Of the 547 measles cases among preschool-age children (Table
3),
285 (52.1%) were classified as not preventable: 219 (40.0%)
children
were less than 15 months old, and 66 (12.1%) had adequate evidence
of
immunity to measles. Of the 262 children with potentially
preventable
measles cases, 239 (43.7% of the total 547) were not listed as
attending day-care centers and thus were not readily accessible to
control measures. Therefore, only 23 (4.2%) measles cases
occurring
among the preschool-age children were both potentially preventable
and
in children readily accessible to control measures.
Reported by participating state and local immunization programs;
Immunization Div, Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: This analysis represents the first time that
information has been analyzed on a national basis to determine the
potential preventability of reported measles cases and the
accessibility of patients to school-based control measures.
Limitations of the data must be taken into consideration in the
analysis. Case reports were derived from a nonrandom sample of the
total reported measles cases in 1981. Completeness of reporting
varied among the reporting areas. If no immunity status or prior
history of physician-diagnosed measles illness was provided, it was
assumed that the person did not have adequate evidence of immunity
to
measles. If no day-care center was named, it was assumed that a
preschool-age child did not attend a day-care center. Furthermore,
incidence rates by vaccination status and day-care-center
attendance
cannot be determined because the denominator populations are not
known. Nevertheless, the data are helpful in evaluating areas in
which further emphasis in the measles elimination program should be
placed.

A majority of cases occurred in the school-age population, a
group
that is easily accessible to control measures. The higher
proportion
of preventable cases in older children suggests that health
authorities should continue to concentrate efforts on ensuring that
junior and senior high school students have adequate evidence of
immunity to measles.

Preliminary data indicate that although the actual number of
cases
in the preschool population decreased from 1980 to 1981, the
proportion of cases occurring among preschoolers increased because
of
greater reductions in the number of cases among school-age
children.
This might have been expected since a major focus of the measles
elimination effort is on school-law enforcement.

It is also expected that most preschool children who have
measles
are not attending organized day-care centers since many states have
and enforce measles-vaccination regulations for day-care centers.
Additional strategies implemented to improve immunization levels in
preschool children include: postpartum maternal education programs,
tracking systems for infants deemed to be at high risk of lacking
vaccinations, recall systems for children who miss appointments for
vaccinations, and intensive case containment activities.
Additional
efforts may be necessary to locate and vaccinate preschool children
in
those few areas of the country where substantial numbers of
preschool
cases are reported.
*Potentially preventable case--measles illness occurring in a
person
at least 15 months of age and born after 1956 who lacked adequate
evidence of immunity to measles.
Adequate evidence of immunity--history of live measles vaccine on
or
after the first birthday (date of vaccination must be specified) or
history of physician-diagnosed measles illness.
Accessibility to control measures--enrollment in a recognized
day-care
center or age 5-19 years (old enough to attend school).

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